| Question | Answer |
| Apical Ectodermal Ridge (AER | stimulate extension of limbs
CC:Remove AER leads to limb defects
Thalidomide inhibits proliferation and interupts the AER functioning |
| FGFR-3 | Lengthening of limbs
CC: Disruption leads to dwarfism |
| HOX | Segmentation - Provides address for limbs CC: Results from failure of webs to degenerate (ie failure of cell death/apoptosis).
Limbs in wrong places
Klippel-Feil
Brevicollis
Syndactyly |
| WNT7a | Organization along Dorsal-Ventral axis |
| ZPA | Morphogenic control region located at the base of the developing limb bud. Regulates differentiation of digits. |
| MyoD | Induces muscle development
CC: Prune Belly, Congenital Torticollis, Poland Syndrome |
| PAX6 | Patterning of neural tube Basal - Primary
Motor-efferent |
| SHH | patterning along anterior-posterior axis |
| PAX3 | Patterning of neural tube Alar-sensory- afferent |
| Joint formation | Type depends on extracellular matrix secreted |
| Synovial joint | Central mesenchyme disappears to form cavity (depends on movement)
(diarthrosis) - freely moveable joints are the most common found |
| Fibrous joint | like sutures of the skull
synarthrodial - immoveable joints found in cranial vault and teeth |
| Cartilaginous joint | Hyaline or fibrocartilage formed; synchondroses and sympheses - partially moveable joints
Ex: costochondral joints, pubic symphysis |
| Joint movement - hinge | Flexion/Extension; elbow/knee |
| Joint movement - pivot | Rotation of one bone around another; neck, atlas and axis bones |
| Joint movement - ball and socket | shoulder and hip |
| Joint movement - saddle | thumb |
| Joint movement - condyloid | Wrist joints |
| Joint movement - Gliding | Gliding movements; intercarpal joints |
